Field of the Invention
Embodiments of the present invention generally relate to a method for forming a micro-electromechanical systems (MEMS) device and a MEMS device formed.
Description of the Related Art
MEMS devices typically include a movable plate (i.e., switching element) that is movable between multiple positions, such as between a position in close contact with an electrode and a position spaced from the electrode. Some MEMS devices are used in digital variable capacitors (DVC).
Some DVC devices are based on a moveable MEMS element with a control-electrode above (i.e., a pull-up or pull-off or PU-electrode) and below (i.e., a pull-in or pull-down or PD-electrode) the moveable MEMS element. In addition there is an RF-electrode below the moveable MEMS element (i.e., switching element or switching member or plate or cantilever or movable plate electrode). During operation a voltage is applied to either the PU or PD-electrode, which causes the MEMS element to be pulled-up or pulled-down in contact to provide a stable minimum or maximum capacitance to the RF-electrode. In this way the capacitance from the moveable element to the RF-electrode (which resides below the moveable element) can be varied from a high capacitance Cmax when pulled to the bottom to a low capacitance Cmin when pulled to the top.
To form the MEMS device, the switching element is disposed within a cavity and partially surrounded by sacrificial material that is later removed. Removing the sacrificial material may lead to the etchant interacting with the conductive material of the switching element. Thus, a dielectric material may be formed between the sacrificial material and the switching element. The dielectric material and the sacrificial material may not adhere well to one another and thus, the dielectric material may delaminate from the sacrificial material, which leads to poor device fabrication conditions.
Therefore, there is a need in the art for adhering sacrificial and dielectric material in a MEMS device.